1. Field of the Invention
The invention relates to cast-molding polymeric resins and more particularly relates to a method of molding very thin (eggshell type) components for model making.
2. Brief Description of the Prior Art
It was known prior to my inventon to mold by casting techniques, component parts for modeling including thin bodies. However, the prior art techniques and methods have not been entirely satisfactory for a number of reasons. For example, it has heretofore been difficult to obtain relatively large cast bodies having uniform thickness throughout the body members. If the body in its use, for example as a fuselage component for a model airplane, is subjected to various physical stresses the heterogeneous body is likely to fracture. If the body member could be made more homogenous in thickness, the likelihood of fracturing under the same stress conditions is substantially reduced.
By method of the invention, thin (0.010" to 0.060"), members may be cast molded in any desired size and configuration. The body members so produced are of a controlled, homogeneous thickness throughout and may include integrally molded bulkheads, inserts, trays and like support members. In reinforced castings such as fiberglass fabric reinforced polyester castings. The glass fiber fabric to resin ratio is more uniform throughout the cast body, facilitating the production of thinner, lighter and stronger castings. The ease of control of resin distribution throughout the mold assures a homogenous structure which will expand and contract uniformly with changes of temperature, reducing to a minimum the deflections now observed in prior art castings.
The method of the invention also facilitates the use of more intricately detailed molds with finished surfaces, thereby reducing hand work required to finish the casting. Through use of the method of the invention, it is possible to reduce the cost of assembling parts and to reduce hand labor often required by distortion of cast parts made by the prior art techniques. Mass production capabilities are advantageously employed with the method of the invention. Further, because bulkheads and like support members are integrally formed or fused with the body member casting, there can be a considerable weight saving over the prior art methods, which often require the installation of heavy bulkheads and support members made out of plywood or like materials.